The Yellow Truth
by GoldGuardian2418
Summary: A nightmare Rachel has and a part of Sans' past are linked. Can they put it to rest or will it change their friendship?


**I was thinking about the other souls Asgore had trapped before they were all released and this story bit me and wouldn't let go. :)**

 **Undertale belongs to Toby Fox. Ben 10 belongs to Cartoon Network and Man of Action. Summer belongs to VinnieStokerLover. I only own Rachel.**

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 **The Yellow Truth**

Rachel bolted upright in bed, gasping in fright as she took some deep breaths, her room coming into focus after she had turned on a nearby light on her nightstand. She then got up and moved very quietly to check on the few aliens and her daughter.

Snare-Oh, Clockwork, Nanomech, and Big Chill were all sleeping peacefully and Summer was also sound asleep in her room, but had kicked off the covers in her sleep. Smiling, Rachel gently replaced the covers over her daughter, gently kissing the five-year-old's forehead. Heading back to her room and seeing it was one o'clock in the morning, she sat on her bed and picked up her phone. Her worry wouldn't go away and she knew it wouldn't until she called him. Pulling up her contacts, she selected his number, hoping he'd forgive her for calling so late.

Sans was awake and laying on his bed when he heard his phone buzz and he picked it up, seeing Rachel's number. Smiling, he answered. "I know Rook's on a mission and most of the others are out doing stuff, but surely you're not too _bonely_ that you had to call this old sack of bones," he said.

A chuckle on the other end made him smile before he heard Rachel become somber again. "Sans? Is everyone okay there?" She asked. "Is anyone hurt?"

Curious by her questions, Sans sat up a bit more. "Yes, everyone's fine," he said. "Why? What happened that you ask that?"

"Are you absolutely sure everyone's okay?"

He heard her voice shake and something told him she was afraid of something. "Hold the phone. I'll take a look," he said, heading out and finding Papyrus asleep in his room and Frisk sound asleep in her room. Undyne was sleeping on the couch, facing the door. Nodding to himself, Sans went back into his room. "Yes, everyone's alright. Pap and Frisk are asleep and Undyne's sleeping over downstairs facing the door. If anyone tries to break in, she'll be on them in an instant."

Rachel sighed in relief and could feel Sans' curiousness over the phone. "Sorry to worry you, Sans," she said sheepishly. "I had a nightmare."

"What happened?" He asked her gently.

She took a moment to remember. "I was standing somewhere and this tall figure was standing in front of you and Papyrus, but they had no features, kind of like a shadow and…the figure hurt you two. They thrust forward and Papyrus fell and you fell right after and both your powers seemed to go haywire and shot out like how a firecracker would burst and the sound of it made me jump and I woke up," she said.

Sans didn't like the sound of that and was about to ask Rachel something when she gasped. "That necklace," she said. "A skull with a knife through it."

The joke-loving skeleton froze and knew if he had blood, it would have run cold. He had seen a necklace like that a long time ago, maybe a few years after the monsters had been banished to the Underground. The adult male that had fallen into the Underground wearing the same necklace Rachel described. The yellow soul.

"Sans?" Rachel questioned, hearing him go silent.

He ran a hand over his skull. "William," he said. "He fell into the Underground and he had that same necklace."

Rachel went to her computer and pulled up her family history. "Another person of my family wore that necklace too," she said. "A distant cousin from my birth father's side, I think."

She then found what she was looking for. "William was my fifth cousin seven times removed," she said and then paused. "Sans, how did you know his name?"

The skeleton didn't answer right away. "Meet me downstairs in your living room," he requested after a moment.

Rachel went downstairs and found Sans already there, wearing his blue hoodie with a gray t-shirt and blue shorts, making her guess that he had been in bed when she called him. Sans sighed and gestured to the couch, sitting down and Rachel immediately sat beside him. "What do you know about him?" He asked her.

"All I found out was that he had a psychological disorder and it was difficult for him because his personality would change at the drop of a hat," she said. "But his death is marked 'unknown', which is rather strange."

"Why is that?" Sans asked.

"He's the only one who's death isn't clarified," Rachel said. "But from my family tree, he had children and had made two necklaces that had skulls with knives in them and wore one while his daughter wore the other and the necklace was always given to the daughter's daughter. I remember seeing it once when I was much younger because it looked terrifying and I asked her what it was supposed to be and she said it was telling people what she'd do if she saw a monster. According to my family tree, she died almost a hundred years ago in a terrible accident."

The skeleton beside her sighed. "And William died one-hundred and eighty years ago," he said. "The human with the yellow soul."

Rachel turned to Sans. "What?" She asked.

He looked at her. "Remember when I told you about the monsters needed a soul with each of the seven traits to break the barrier in the Underground?" He asked.

She nodded. "And you saw my sister and I had rainbow-colored souls, meaning we have all the traits," she said.

He nodded. "William was the second one that fell in the Underground and we picked up on his psychological disorder and kept a close eye on him, but he nearly hurt us many times," he said.

Rachel took a deep breath and gave Sans a serious look. "Did you…? Or the others?" She asked.

He shook his head. "His death was accidental," he said. "He had fallen onto some sharp rocks in his battle with Undyne and was instantly killed. As we stood there, Asgore took the yellow soul to his castle and it stayed there until Frisk freed us and the souls were released."

The skeleton looked down in grief. "He was the first human I'd ever seen die and I never wanted to witness that again," he said. "He was so hesitant, but mostly just frightened. He never wore the look of a murderer."

The young woman looked at him. "What makes you say that?" She asked.

"When he tried to hurt us, he had an unsure look in his eyes, like he was so confused. He even held the knife wrong many times," Sans said. "We…We just couldn't help him, even though we tried."

He had leaned back on the couch as if explaining it had exhausted him and Rachel now leaned back so that she was snuggling into Sans' side and he automatically began stroking her shoulder in comfort. "You tried to show him you weren't going to hurt him," she said softly.

He nodded and she looked up at him. "Sans, I'm not going to blame anyone for his death because no one is to blame. Like you said, it was an accident. And his disorder really didn't help matters."

Sans looked at her again, nodding softly and Rachel remembered something. "If his soul was yellow, isn't that the color of the trait Justice?" She asked.

"Yes," he said.

She looked a bit confused. "But yellow can also mean a coward, right?"

Sans nodded. "But your relative wasn't a coward," he said. "He just didn't know exactly how to deliver that justice and his disorder made that harder for him, but…he did have some good in him."

Seeing Rachel was listening, he smiled a little. "He tried to save Gaster," he said. "But he wasn't strong enough to do so and I think that really hurt him, because he could hear Gaster, but couldn't save him."

The owner of the Grant Mansion nodded in agreement. "Maybe he was hoping that he could do something and succeed for once," she said as she called up her family tree on her phone and put down the death of her distant cousin as accidental, nodding after it was done, glad that the matter was now put to rest.

Sans looked at her again. "Rachel, does this…change anything?" He asked.

She shook her head. "No," she said. "Like I said, no one is to blame and William has been put to rest. This doesn't change anything."

Feeling relieved, he sighed. "Y'know, I used to think that term 'lifting a great weight of my shoulders' was metaphorical, but it's got some _weight_ to it," he said, chuckling along with Rachel. "By the way, there's something I needed to tell you."

Staying in her spot, Rachel snuggled closer to Sans, who returned the snuggle, thinking of the young woman as a younger sister. "Rook came to see me the other day and he asked me to take care of you and the others if anything happened to him," he said.

The young woman nodded. "Rook and I discussed that too and decided that we could trust you and the other monsters and a few humans to keep us all safe if anything happened to the Grant Mansion family," she said.

Sans nodded. "You and all your family members will have a place to stay with us if anything should ever happen," he promised her. "But _tibia_ honest, I hope nothing does ever happen."

Rachel nodded and they were both quiet for a bit until they heard someone softly approaching and saw Summer come into the room, spying them quickly. "Mommy? Uncle Sans?" She asked.

The older woman sat up. "What's wrong, sweetie?" She asked, picking up her daughter. Sans sat up too.

"I had a scary dream," Summer said sadly. "I couldn't find you, Daddy, or anyone."

Rachel hugged Summer close. "I'm here, sweetheart," she said softly.

Seeing Sans there too, the five-year-old reached for him and Rachel let her go so that the little girl could hug the skeleton, who returned the hug, rubbing her back soothingly. "No one's leaving you, kiddo," he said.

As she settled down, Sans perked up a moment. "Hey, Rach, can I see something?" He asked.

Knowing what he meant, she nodded and the rainbow heart was soon in Sans' gentle grasp and he examined it and smiled after a moment. "You carry justice with you, something that I believe deep down William carried too," he said as he let go of the heart and it returned to Rachel.

Summer, who had been told about Sans' power and a monster's ability to see a person's strongest traits, looked up at Sans. "What's my strongest trait, Uncle Sans?" She asked.

He smiled. "You and your brother have rainbow souls just like your parents," he said.

The little girl smiled before yawning a bit, making the two adults smile and they put her back to bed and Rachel allowed Sans to crash in her room. "Sans," she said. "Thank you."

He smiled. "No problem," he said as he lay on Rachel's bed and fell asleep instantly. Rachel followed suit as the night became peaceful once again.

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 **I know. Not quite a lighthearted story, but I hope you all liked it nonetheless. :)**

 **Please leave a review, but no flames!**

 **GoldGuardian2418**


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